What're her tastes? Would she like something simple or something that grabs attention? How important is protection to her? There's a difference between scratch protection and impact absorption.
My mom uses a Switcheasy Glitz, one of my sisters uses a Switcheasy Trim (I would recommend this or the Glitz pending her tastes), my other sister uses a CapsuleRebel, and my gf likes her iPhone naked. One of my friends uses an Otterbox Commuter and my sister's bff uses a Defender, and neither of those are exactly "girly" looking cases. Tastes are subjective and theres no one true "gf/wifey" case.
I use a devilphone back skin and a rocketfish frame bumper.
At the moment I dont use a front shield as I'm not keen on the difference in feel on the screen.
Stay clear of Zagg. They are notoriously hard to fit and give an orange peel look. Thats my own experience. On balance some users have reported no issues in fitting and like the orange peel look.
If you're willing to spend about $20 more, you could buy one of these beautiful Vaja cases... Really beautiful, great reviews. the downside is, although there are some designs ready to ship out, some of the other designs take about 20 days to make :/ But if i didn't mention it already, they are beautiful beautiful cases, and certain worth the wait (except for the first case displayed on the bottom). OOOOOogly